ARM: OMAP2+: hwmod: Hook-up am33xx support in omap_hwmod framework

AM33XX PRCM architecture is different that any OMAP family
of devices, so it is required to have separate implementation
to handle AM33XX module enable/disable, reset assert/deassert
functionality.
This patch adds wrapper api's in omap_hwmod framework to
access prm/cm for AM33XX family of devices.

Signed-off-by: Vaibhav Hiremath <hvaibhav@ti.com>
Cc: Paul Walmsley <paul@pwsan.com>
Cc: Kevin Hilman <khilman@ti.com>
Cc: Tony Lindgren <tony@atomide.com>
[paul@pwsan.com: fixed checkpatch messages]
Signed-off-by: Paul Walmsley <paul@pwsan.com>